The present invention provides a novel fluorescent protein the wavelength of the maximum of the fluorescence of which exists in a wavelength side longer than 510 nm, and which exhibits yellow fluorescence or yellowish green fluorescence and can be expressed in a heterogeneous cell, and a gene encoding the same, wherein the fluorescent protein has an amino acid sequence as set forth in SEQ ID NO: 1 and it is a fluorescent protein derived from a copepod taxonomically classified to Chiridius Poppei.